Spain's overlooked artists. Also, composer Arnold Schoenberg's other talent

No country has made a greater contribution to 20th- century art than Spain. Picasso, Miro, Gris, Gonzalez, and Dali were born there, and several other excellent modernist painters and sculptors trace their roots to that country.

The worldwide fame and fortune enjoyed by these figures was not shared, however, by another group of Spanish painters of the 1850-1950 period. The reputations of these artists seldom extended beyond Spain and France, and when, upon occasion, they did exhibit elsewhere, their work was generally unfavorably compared with that of their more famous contemporaries.

An excellent opportunity to discover how fairly they were treated has been afforded the American public by the Modern Art Museum in Barcelona, which organized and sent ''Spanish Painters in Search of Light'' to the National Academy of Design here. This exhibition of 57 paintings by 23 artists consists of landscapes, figure studies, seascapes, and cityscapes, documenting Spanish art's attempts to solve the problem of painting light and atmosphere that had also challenged the French Impressionists and Neo-Impressionists.

Outstanding in this group were Joaquin Sorolla (1863-1923), Mariano Fortuny ( 1838-74), Aureliano de Beruete (1845-1912), and Daniel Vazquez Diaz (1882-1969), with Munoz Degrain, Carlos De Haes, and Eduardo Rosales also contributing a number of excellent pictures. All were painters in search of ways to depict form and image by means of light rather than by line. Their commitment to this search was neither as total nor as strictly rational, however, as it was with Monet, Pissarro, or Seurat, with the result that their work now appears more relaxed and much less revolutionary than that of their French contemporaries.

Sorolla's ''Ladies and Child in a Boat,'' for instance, while remarkable in many ways, loses much of its impressiveness when we consider what Renoir or even Sargent could have done with such a scene. And the same is true of the landscapes. They hold their own quite well as long as they aren't compared with what was going on in France at the same time.

Only Fortuny stands largely on his own. His four canvases (one is a collaborative venture with Raimundo Madrazo) are by far the best things in this exhibition; they indicate that a full-scale retrospective of this extraordinary painter is very much overdue.

At the National Academy, 1083 Fifth Avenue, through Jan. 15.

Arnold Schoenberg's Vienna

Were Arnold Schoenberg (1874-1951) not a world-famous composer, his paintings and drawings would deserve no more than a short footnote in any discussion of the arts in Vienna during the early years of this century. Because of his fame, however, as well as his deep involvement with that city's cultural life, his roughly 250 works on wood, canvas, cardboard, and paper achieve some importance by presenting an additional insight into his innovative genius, as well as a glimpse into the world inhabited by such major contemporaries of his as Mahler, Berg, Schiele, Klimt, Kokoschka, Gerstl, and Kandinsky.

Thirty-seven of the composer's paintings and drawings, together with several important pictures by Kokoschka, Schiele, Klimt, and Gerstl, make up a fascinating exhibition now on view at the Galerie St. Etienne here. ''Arnold Schoenberg's Vienna'' explores the relationship between the musician and these four painters within the context of Viennese cultural and social life, and does so in a manner that gives Schoenberg his full due without claiming more for him than he deserves.

For this, the gallery was able to draw upon the resources of the Arnold Schoenberg Institute at the University of Southern California, which houses his entire artistic legacy, as well as public and private collectors in the United States and Austria. The result is a small but excellent exhibition of particular value to anyone interested in the beginnings of modern music and Austrian Expressionism.

Schoenberg began to paint in earnest in 1908, shortly after the suicide of his friend Richard Gerstl, a young painter who had encouraged the composer and his wife to try their hands at painting. Despair over his friend's death led Schoenberg to compose his first ''atonal'' songs and to take painting more seriously. His first exhibition in 1910 was not a success, however, partly because the press attacked it as mercilessly as it did his music. Even so he persevered, and in 1911 Kandinsky saw to it that his paintings were featured prominently in the first ''Blaue Reiter'' exhibition. Although an entire room was given over to his pictures in a Budapest show the next year, Schoenberg decided it was impossible to achieve true mastery in two art forms, and he turned from then on to music. His interest in painting and drawing did not completely desert him, however, as is evidenced by the occasional study or sketch he turned out in odd moments over the succeeding years.

Of particular interest in this show are several of Schoenberg's self-portraits, his landscapes, Schiele's drawings, Kokoschka's landscape, and Gerstl's large portrait of the seated composer.

At the Galeries St. Etienne, 24 West 57th Street, through Jan. 5.

Enzo Cucchi

Enzo Cucchi's recent exhibitions at the Sperone-Westwater and Mary Boone galleries should have convinced anyone still in doubt that this younger Italian Neo-Expressionist is a force to be reckoned with. Like many of his contemporaries in Europe and America, he has Big Ideas, which he insists be given maximum impact in canvases that are huge, blatant, and aggressive. Unlike many of his contemporaries, however, Cucchi's ideas are often worthy of such size and aggressiveness. They may not always be verbally communicable, but they produce powerful and provocative images of the sort usually only encountered in dreams and in such works as Rousseau's ''Sleeping Gypsy'' and Redon's lithographs.